Yi Dou

National Institute for Environmental Studies

Research AssistantEco-society Innovation Section,Center for Social and Environmental Systems Research,National Institute for Environmental Studies

Abstract

This research focuses on the role of a system for the recovery of energy from municipal solid waste to create a symbiotic network among the actors in multiple sectors, namely power plants, energy-intensive industries, process... [ view full abstract ]

This research focuses on the role of a system for the recovery of energy from municipal solid waste to create a symbiotic network among the actors in multiple sectors, namely power plants, energy-intensive industries, process industries, ICT industries, agriculture, offices, public buildings, and housing. From the practical and academic perspectives, energy from municipal solid waste, including plastics, paper, and food, can be recovered by using waste-to-energy technologies through a framework of industrial and urban symbiosis, fourth-generation district heating, and smart grids. The aim of this research is to identify how we can redevelop energy systems in accordance with thermodynamic principles, such as exergy theory, to approach the development of low-carbon cities by using technological modeling in accordance with thermodynamics theory and application of the model to targeted cases.

Three options to recover energy from incineration system were targeted that can be explained by basic thermodynamics; that a large energy saving can be realized if industry uses high-temperature and pressure heat. The first option is direct supply of high- pressure and temperature steam to industry. We map the network among incineration plants and the plants of chemical, pulp, and ceramic industries, 77 routes are physically feasible. We revealed that half of the feasible projects are concentrated in coastal industrial zones in Tokyo metropolitan. A more detailed analysis of steam supply network among industries has been conducted in the Kitakyushu coastal area. This case can be estimated to achieve 82 Mton-CO2 and 1.05 billion JPY reduction per year with 1.8 billion JPY initial investment. The second technological model is highly efficient electricity generation by using a combined waste-to-energy technology. Boiler steam is heated by methane combustion in super-heating equipment, and the heated steam is fed into a power generator. In the individual super-heater, methane gas made in the methane fermentation plant adds extra heat to raise the steam temperature and pressure, thus increasing the generation efficiency. We have developed a thermodynamic balance model and revealed the effects and a model to analyze the costs and benefits of the system. The results shows the amount of energy recovered from a combined system was 54.5 kWh/t, and the efficiency was 33.4%, which is much better than 12.2 kWh/t and 13.2% in an individual system. The third technological model is the use of low-pressure and temperature water in urban districts. One of the candidate heat suppliers is incineration plants that can supply hot water after sufficient electricity has been generated.

As future challenges, the first is to develop a framework for assessing the costs and benefits of combinations of technological options for municipalities with differing local characteristics. Second, we need to do a scenario analysis of public policy and business models, including the subsidy system, the pricing mechanism (for example, FIT), financial support, and risk sharing scheme. Third, we also need to develop a cost-benefit allocation theory from the microeconomic and life-cycle perspectives. And lastly, we need to design a process for mining social data from stakeholders by using a computer simulation interface.